CELL BIOLOGY: Picket Fences

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Science  11 Jul 2003:
Vol. 301, Issue 5630, pp. 143c
DOI: 10.1126/science.301.5630.143c

Neurons represent an exquisitely complex type of polarized cell. They possess three radically different domains—dendrites, cell body, and axon —and each of these has a distinctive surface composition. How the neuron maintains this polarized distribution has been the focus of many studies, sometimes with conflicting results.

Nakada et al. have examined the dynamics of lipids in developing hippocampal neurons. They observed the formation of a diffusion barrier for lipids at the axonal initial segment (IS)—the point at which the axon emerges from the cell body. The barrier appears to be imposed by the accumulation of membrane proteins anchored in a meshwork of actin below the membrane. These anchored proteins serve as a kind of picket fence to restrict the diffusion of membrane lipids. This mechanism may be important generally when cells need to establish connected but distinct membrane domains. — SMH

Nature Cell Biol. 5, 626 (2003).

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